The present invention relates to trialing devices used during knee replacement procedures to size and prepare a resected tibia for receiving a tibial implant and to evaluate the stability and kinematic performance of the articular surface provisional prior to implantation of the tibial implant.
Generally, the knee is the joint between the femur and the tibia. The knee joint is formed of a pair of condyles located at the distal portion of the femur, a tibial plateau located at the proximal end of the tibia and shaped to mate with the pair of condyles, and a pair of menisci positioned between the tibial plateau and the condyles. The femur and the tibia are connected by ligaments, which provide stability to the knee. Such ligaments include the posterior cruciate ligament (PCL), the lateral collateral ligament, the medial collateral ligament, and the anterior cruciate ligament. Significant disease of, or trauma to, the knee may warrant replacement of the knee with a prosthetic knee (knee implant).
A prosthetic total knee joint generally includes a femoral component and a tibial component. The tibial component typically includes a tibial tray or plate and a prosthetic bearing insert. The tibial tray often includes a stem, which extends from the bottom of the tray and is sized for insertion into the tibia. In some knee implants, the bearing insert may be fixed to the tibial tray such that the bearing insert is immobile relative to the tibial tray. These knee implant designs are often referred to as “fixed bearing” designs. In other knee implants, the bearing insert is movably fixed to the tibial tray thereby allowing the bearing insert to move relative to the tibial tray. These knee implant designs are typically referred to as “mobile bearing” designs.
During mobile bearing knee replacement surgery, the surgeon first prepares the proximal end of the tibia by resecting the proximal tibia or, in the case of revision, removing the damaged tibial components prior to resecting the proximal tibia. After the tibia is prepared, a tibial sizing plate is aligned and placed on the resected tibia, and checked for size. After the proper sizing plate is selected and the optimal location is determined, the sizing plate is fixed in position on the resected tibia by inserting pins through the sizing plate and into the resected tibia. The pins generally have cap heads that remain extended above the surface of the sizing plate so that the pins can be extracted upon completion of the trial. Next, the surgeon selects an articular surface provisional, which is modeled in shape and design after the bearing insert of the tibial component that the surgeon proposes to implant. The surface provisional is then engaged with the sizing plate. With the articular surface provisional in place, the surgeon then performs trialing procedures to test the fit and function of the articular surface provisional. Such trialing procedures may include measuring the flexion and extension gaps, and conducting range of motion tests, during which the anterior/posterior and medial/lateral stability and movement may be tested. These trialing procedures help the surgeon determine the proper sized bearing insert. The surgeon may repeat the trialing procedures with different sized provisionals until the desired results are achieved.
Next, the surgeon removes the pins and the sizing plate. A broaching plate is then positioned and carefully aligned on the resected tibia such that pin holes in the broaching plate are aligned with the pin holes created in the tibia by the mounting of the sizing plate. Once aligned, the broaching plate is pinned in place. With the broaching plate in place, a drill/broach guide is engaged with the upper surface of the broaching plate and the proximal tibia is drilled and/or broached to accommodate the tibial stem of the tibial tray.
There is a need for a tibial trialing device that simplifies and minimizes the steps of knee replacement surgery.